1. Field of the Invention
As smart devices, e.g., smartphones and wearables, have become multi-functional and lighter in weight and mass, heat management of the device becomes more and more important. How heat production can be reduced or removed from components, such as transistor, back light module and battery is a crucial task for overall design and structure of these devices. This disclosure is directed to composites of copper foil and graphene, structures embodying the same and methods of heat management of smart devices utilizing these composites and structure in managing heat created by these devices.
2. Description of the Prior Art
Until now, pyrolytic graphite sheets were used as a heat dissipation component. However, pyrolytic graphite sheets are very expensive to manufacture, as well as being very brittle and very easy to crack or shatter. Pyrolytic graphite sheets are made from a polyimide (PI) film by a two-step process. The first step is a carbonization process, which is conducted at a 1000° C.˜1400° C. environment, in which the PI film changes color from brown to black. The second step is the graphitization step, which is conducted at 1800° C.-3000° C. environment, in which the carbon atoms rearrange into the graphite structure. Pyrolytic graphite sheets are also very brittle and tend to crack or shatter during transport and handling, especially during handling during installation on electronic devices. The energy costs associated with the high temperatures of production are very costly, especially if there is a high loss rate of the resulting graphite sheets due to cracking. Thus, there exists a need to provide less costly and structurally better alternatives to pyrolytic graphite sheets as a component for heat dissipation.
Graphene production is described in U.S. Pat. No. 7,071,258, the entire disclosure of which is herein incorporated by reference. Graphene can be produced by partially or fully carbonizing a variety of precursor polymers, such as polyacrylonitrile (PAN) fibers and phenol-formaldehyde resin, or heat treating petroleum or coal tar pitch, exfoliating the resulting carbon- or graphite-like structure and mechanical attrition (e.g., ball milling) of the exfoliated structure to become nano-scaled. Although the foregoing patent describes incorporation of the nano-scaled graphene plate (NGP) material into a matrix material to obtain an NGP-reinforced composite, there is no disclosure for making graphene coated metal sheets, and no disclosure of copper foil/graphene composites.